Telephone system



Nov. 29, 1932. J. F. McELHOLM TELEPHONE SYSTEM 2 Sheefs-Sheet 1 Filed May 19, 1932 Nov. 29, 1932.

J. F. McELHOLM 83 TELEPHONE SYSTEM Filed May 19, 1952 2 Sheets-Sheet 2 m7" Nvlmg nlt I 1 BY 2 fiwamm ATTORNEY Patented Nov. 29, 1932 TES - UNITED STA JAMES F. MCELHOLM, LOWELL, MASSACHUSETTS TELEPHONE SYSTEM Application filed. May 19, 1932. Serial No. 612,239.

This invention has to do with the well known arrangement of telephone systems in which ordinarily there is a central exchange with various connections all of well known construction. From the central exchange radiate difierent telephone lines or stations, connections between which are made at the central exchange.

In such systems when there is a call to the a. central exchange for a certain line, the hell on that line rings at a station. I will call that the primary receiving station.

In many cases, there is what is known as an extension line from the primary station or from the central exchange to What I will call a secondary station.

With the usual arrangement of connections, when the receiver at the primary station is removed from its holder and it appears that someone at the secondary station is wanted, such person must be' called'and'the'receiver kept from its holder at the primary station until the person at the'secondary station has removed the receiver at the secondary station from its holder upon which the primary receiver should be put back on its'holder.

The purpose of thisinvention is'to provide locking mechanism at the primary station of such character that when the receiver holder rises upon the removal ofcthe receiver, the locking'mechanism will automatically hold it up until unlocked by electrical devices electrically connected with the secondary station. The receiver at the primary station can, therefore, be replaced on its holder and the person at the primary station can leave it.

' At any timethereaftenthe'person at the secondary station by pressing a push button can unlock tlie'locking mechanism and allow. the receiver and receiver holder at the primary station to fall down to their normal positions. I 1 Such electrical, push button or switch mechanism may also preferably be automatically operable when the receiver at the, secondary station is removed or if no one is at the secondary station,cthere is preferably a release button at the primary station by pressing which these parts fall back to their normal positions.

In the drawings, Fig. 1 is a view of a combination receiver, transmitter at a primary station, with parts broken away to show the construction, associated with a receiver and a transmitter at asecondary station together with some them.

. Fig. 2 is an enlarged sectional view on line 22 of Fig. 4 looking in the direction of the arrow and with the receiver locked in the GO up position.

Fig. 3 is a view similarto Fig. 2 with the receiver in the down or normal position.

Fig. 4 is an enlarged view looking up from under the standshown inFig. 1, the wiring between the switches at the primary and sec onldary stationsbeing shown diagrammati cay.

Fig. 5 is aview similar to Fig. 1 of a modi fication of the locking arrangement at a primary station with a transmitterand receiver of a somewhat different type fromthat shown in Fig. 1 and wire connections to a secondary station with another type of switch.

Fig. 6 is a sectional view lookingdown on parts of the wiring connecting line,66 of Fig. 5.

Fig. 7 is an elevation ofv the locking mech anism casing looking from the leftof. Fig. 5 and shown as somewhat'enlarged.

Fig. 8 is a sectional view looking in the direction of the arrowv on line 88 of Fig. 7.

Fig. 9 is a detail elevation of a modified form of locking mechanism as itwould appear looking from the left of Fig. 5 with part of the tubular casingbroken away to show the interior.

. In the drawings, P representsa primaryreceiving station connected by wires .W with a central exchange and S represents a secondary station connected by wires X either with the wires W or with the central exchange, but ordinarily the wires X are tapped into the wires W in a well known manner.

The transmitter 3'and the receiver 4 at the primary station, as shown, are, of the comreceiver holder 5 is vertically movable on a stand 2.

All of the above are of the usual construction and the electrical connections which are not shown are of such a character that the weight of the receiver depresses the holder and keeps the primary station open to receive calls. In Fig. 1 the receiver and transmitter are connected together. The term re ceiver is used in a more general sense than where the receiver and transmitter are separated.

At the secondary station S, the transmitter 7 and receiver 8 are shown as of a different type from 3 and 4, receiver 8 resting on a holder 9 shown as a pivoted arm.

At the primary station is provided automatic locking mechanism L, the particular. type shown including an armature pivoted at '50. One branch 51 of armature 49 is formed so that it can move in and out from under a collar forming part of theleg 1 which supports holder 5.

The spring 52 tends to force branch 51 under leg 1 so that when the holder 5 and its leg 'lare lifted by lifting means such as spring 6, the receiver holder 5 is locked in the raised position.

'53 is the other branch or locking arm of armature 49 and 54 is a magnet placed in such position that when it is energized by current running through the conductors 5'5, 56, 61, 62, 157 and 57, it will attract the branch 53 thus removingthe branch '51 from under leg land allowing the holder 5 to drop, if the receiver 4 is on it, as the weight of the re.-

ceiver more than counter-balances the liftin mechanism 6.

, Magnet 54 isshown as supported by an arm 254 attached to stand 2 in any suitable manner and shown as insulated therefrom by insulation 154. Armature 49 isshown as pivoted on a stand 249 attached to stand '2 in any suitable manner and "shown as insulated therefrom by insulation 149.

58 is amanually operable switch, shown as a push button associated "with the secondary station '8 and connected with a suitable source of electric energy such as 60, and 59-is a manually operable switch or push button associated with the primary station P, these switches and the wires 55, 56, 61, 62, 157 and 57 being so arranged that by pressing either switch-58 or 69, the :nragnet 5'4 is energized and the locking'mechanism is released.

Switch '58 doses one circuit through 55, "157, "57, '54, 6'1, 56 and "switch 59 closes another circuit through '55, '1-57. 57, 611, 62.

Locking mechanism L can,there"fore, be released at either the primary .or at the secondary station. v V ""InFigs. 5, '6, 7 and 8 is shown the device adapted for use with what might be called theoldstyle transmitter and associated with it an automatic release at the secondary station.

In Figs. 5, 6, 7 and 8, A represents "the primary station with the usual wiring C and B represents the secondary station with suitable wiring D connected with the primary station in the customary manner.

23 is the transmitter of one type carried by a stand 22 which rests on a base 122 while 25 is the receiver holder for a receiver 24, the receiver holder 25 being kept normally raised as by spring 126 except when the receiver 24 rests upon it, when it drops.

F represents broadly the mechanism to automatically hold the receiver and receiver holder in the raised position and as shown is of the following construction:

A hollow casing 51 rests on a plate which extends out and can be slipped under base 122 and there is a hook 52 which extends out and is hooked around stand 22 thus ing in such position that the beveled end 16 at the end of a neck 15 on an arm 14 which extends from weight 13 can pass arm 26 by raising it when weight 13 is free to move down, but when 16 passes 26., it cannot return unless arm 17 and its end 26 are raised by the magnet 18.

In this way, when the receiver 24 is removed from the holder 25, head 11 rises to the full line position shown in '5, 16 passing the end 26 of armature 1'1 and then being U locked by'26 until the armature 1 .7 is lifted by the magnet 18. p Y

Only two conductors 19 and '20 are shown between the magnet and the secondary station B. The conductor '20 terminates in a contact in such position that it be engaged by a movable contact 119 connected with conductor 19, contact 119 being carried by one arm 124 of a rocking lever 129 pivoted 2115222 to the stand223 ofthe transmitter 2.24. 1,,

A spring 123 tends to pull contact 119 down to 120 thus completing the circuit 'through asource of electric power Ihe other end of lever '29 is formed :as 'a' receiver holder 121 for the receiver 28.

7 These parts -comprise,'therefore, a 'manu- "W ally operable switch as the electric circuit is closed when receiver 28 'is removed from its holder 121. As shown in Fig. $5, the circuit is open.

By this arrangement, when the receiver 28 is removed from the holder 121, spring 123 brings the contacts 119 and 120together comp'l'eting' the circuit through magnet 18 thus lifting armature 17 :and releasing the end from 26 whereupon the weightxof primary receiver 24 on head 11 depressed head 11 and raises the weighted end 13 bringing the parts back to the normal position and leaving the primary station in a condition to receive calls.

In Fig. 9 I show another modification or" my looking or holding up mechanism for the receiver holder at the primary station.

In this view, 67 represents the stand as a whole including an outside tubular section and an inside fiat section 167 which supports most of the parts. 69 is the receiver holder for a receiver such as 24, these parts being substantially the same as the parts 22, 23, 24, 25 and 26 shown in F ig. 5. Receiver holder 69 is shown as pivoted to the part 167 of the stand 67 at 70 and is normally held in the up position as by a spring 71 similar to 126 except when holder 69 is carried down against the spring 71 by the weight of the receiver 24.

77 is a long, small diameter magnet with a core 76 which is in position to attract the short arm of an angular armature 79 which is shown as carried by a spring 72 attached by screws 73 to the part 167 of the stand.

The long arm'74 of armature 79 is normally pressed by the spring 7 2 up underneath the part 169 of receiver holder 69 whereby when spring 71 raises it, the arm 74 of the armature 79 is pressed underneath thus holding the receiver holder and receiver up until a circuit is completed through magnet 7 7 through the conductors 80 and 81 attached to or connected with a switch of any suitable type at the secondary station.

I claim: 7

1. The combination with a telephone system which includes a plurality of stations connected by electrical conductors, one of such stations being a primary station provided with a transmitter, a receiver, a stand, a receiver holder vertically movable on the stand and means to keep the holder normally raised, all of such character that the weight of the receiver depresses the receive'rholder and keeps the primary station open to receive calls, and a secondary station having suitable electrical connections with the primary station and including a transmitter and a receiver; of mechanism to automatically hold the receiver holder at the primary station in the raised position; and electrical devices for releasing the locking mechanism and to allow the holder with the receiver to drop, said electrical devices being electrically connected with the secondary station and being operative therefrom by a manually operable switch and from the primary station by a manually operable switch.

2. The combination with a telephone system which includes a'plurality of stations connected by electrical conductors, one of such stations being a primary station provided with a transmitter, a receiver, a stand, a receiver holder vertically movable on the stand and means to keep the holder normally raised, all of such character that the weight of the receiver depresses the receiver holder and keeps the primary station open to receive calls, and a secondary station having suitable electrical connections with the primary station and including a transmitter and a receiver; of mechanism to automatically holdv the receiver holder at the primary station in the raised position; and electrical devices for releasing the locking mechanism and to allow the holder with the receiver to drop, said electrical devices being electrically connected with the secondary station and being operative therefrom by a switch which releases the locking mechanism when the receiver at the secondary station is removed from its holder.

3. The combination with a telephone system which includes a plurality of stations connected by electrical conductors, one of such stations being a primary station provided with a transmitter, a receiver, a stand, a receiver holder vertically movable on the stand and means to keep the holder normally raised, all of such character that the weight of the receiver depresses the receiver holder and keeps the primary station open to receive calls, and a secondary station having suitable electrical connections with the primary station and including a transmitter and a receiver; of mechanism to automatically hold the receiver holder 'at the primary station in the raised position; and electrical devices for releasing the locking mechanismand to allow the holder with the receiver to drop, said electrical devices being electrically connected with the secondary station and being operative therefrom by a manually operable switch.

In testimony whereof I afiix my signature.

JAMES F. MoELI-IOLM. 

